Showing papers on "Propulsion published in 2002"

Maneuvering and Stability Performance of a Robotic Tuna

Abstract: The Draper Laboratory Vorticity Control Unmanned Undersea Vehicle (VCUUV) is the first mission-scale, autonomous underwater vehicle that uses vorticity control propulsion and maneuvering. Built as a research platform with which to study the energetics and maneuvering performance of fish-swimming propulsion, the VCUUV is a self-contained free swimming research vehicle which follows the morphology and kinematics of a yellowfin tuna. The forward half of the vehicle is comprised of a rigid hull which houses batteries, electronics, ballast and hydraulic power unit. The aft section is a freely flooded articulated robot tail which is terminated with a lunate caudal fin. Utilizing experimentally optimized body and tail kinematics from the MIT RoboTuna, the VCUUV has demonstrated stable steady swimming speeds up to 1.2 m/sec and aggressive maneuvering trajectories with turning rates up to 75 degrees per second. This paper summarizes the vehicle maneuvering and stability performance observed in field trials and compares the results to predicted performance using theoretical and empirical techniques.

Elements of Spacecraft Design

Abstract: Introduction System Engineering Orbital Mechanics Propulsion Attitude Control Power System Thermal Control Command and Data Handling Communication Structure Appendices

NASA’s Deep Space 1 ion engine (plenary)

Abstract: Ion propulsion is now a legitimate propulsion option for future deep space missions. The long journey required to get from the first laboratory test of an ion engine in 1960 to the first successful flight of an ion propulsion system on NASA’s Deep Space 1 mission in 1998 is briefly summarized herein. An overview of the operation of the Deep Space 1 ion engine is provided along with a description of the complete ion propulsion system on the spacecraft. Engine performance measured in space compares well with that based on ground test data. Future deep space missions desire improved engine performance in the form of longer engine life (greater total impulse) and greater specific impulse. Derivatives of the NSTAR ion engine are being evaluated to assess their capability to meet these future needs.

Trends in ship electric propulsion

Abstract: Since the 1980s there has been an explosion in the number and variety of electric propulsion ships being built around the world with everything from cruise liners to amphibious assault ships adopting electric propulsion. This technology revolution has occurred, largely un-noticed outside the marine industry. This paper briefly describes what has transpired in recent decades, why the resurgence is occurring and what the future may hold for electrically propelled ships.

Far field modeling of the plasma plume of a Hall thruster

Abstract: Hall thrusters are an attractive form of electric propulsion that are being developed and implemented to replace chemical systems for many in orbit propulsion tasks on communications satellites. One concern in the use of these devices is the possible damage their plumes may cause to the host spacecraft. Computer models of Hall thruster plumes play an important role in integration of these devices onto spacecraft as the space environment is not easily reproduced in ground testing facilities. In this article, a hybrid particle-fluid model of a Hall thruster plume is applied to model the SPT-100 thrusters used on the Russian Express satellites. The emphasis of the article is on making assessment of the model through direct comparison with measurements of ion current density and ion energy distributions taken on board Express spacecraft. A model for simulating atom–ion collisions is described. The sensitivity of the plume simulation results to various aspects of the physical modeling is investigated. The plum...

Microairplane propelled by laser driven exotic target

Abstract: We propose a propulsion concept to drive a microairplane by laser that can be used for observation of climate and volcanic eruption. Since it does not have to develop thrust for vertical takeoff, and it has no engine in the normal sense, the microairplane can be very light, with its payload consisting only of observation and communication equipment. In order to demonstrate the concept, we succeeded in flying a paper microairplane driven by a 590 mJ, 5 ns pulse yttrium–aluminum–garnet laser that impinges on a double-layer “exotic target.” The coupling efficiency agrees well with simulations and with experiments.

Control strategy for multiple input DC-DC power converters devoted to hybrid vehicle propulsion systems

Abstract: Customer demands for greater acceleration, performance, and vehicle range in pure EVs plus mandated requirements to further reduce emissions in HEVs increase the appeal for combined on-board energy storage systems and generators. This paper deals with the control system of an original HEV propulsion system that includes fuel cell generator and storage energy system combining ultracapacitor tank and battery. The three on-board power sources supply the vehicle traction drive through a multi-input DC-to-DC power converter which provides the desired management of the power flows. In particular, in the proposed arrangement the ultracapacitor tank is used for leveling the battery load current during transients resulting from either acceleration or braking operation of the vehicle. The paper outlines the features of the control unit of the DC-to-DC power converter being used in the proposed propulsion system and describes the main characteristics of a 35 kW prototype developed to conduct laboratory experiments and validate the control strategy.

Design of the First Interplanetary Solar Electric Propulsion Mission

Abstract: Deep Space 1 was the e rst interplanetary mission to be propelled by solar electric propulsion. The detailed design, development, and analysis of its trajectory have led to important new insights into the design of low-thrust trajectories. Tying the testing of solar electric propulsion technology to an operational mission has allowed the identie cation of trajectory design issues that were not considered in concept studies, such as constraints on the spacecraft attitude and periods of thrusting or coasting that are dictated by reasons other than trajectory considerations. Models of the spacecraft performance unimportant for trajectory analysisin missions using conventional chemical propulsion are intimately connected with the design of the trajectory when solar electric propulsion is employed.In addition, massmargin is notsufe cientto assessa low-thrustmission. Unplanned thrust interruptions may result in a situation in which the propulsion system cannot provide sufe cient impulse to compensate for the lost thrust in time to reach encounter targets. Mission margin (as distinct from mass margin ) is a quantie cation of the mission’ s susceptibility to loss of thrust and is an important indicator of mission robustness for low-thrust trajectories.

Unmanned airborne reconnaissance system

Abstract: An unmanned airborne reconnaissance system, the unmanned airborne reconnaissance system including a lightweight, portable, powered aircraft and a foldable launch rail, the aircraft, in a broken down condition and the launch rail in a broken down condition fitable inside a box, the box capable of being carried by one man. The launch system includes an elongated launch rail with the carriage assembly, and a propulsion means for accelerating the carriage assembly from one end of the launch rail to the other. The carriage assembly releasably engages the aircraft so as to propel the aircraft from one end of the launch rail to the other. The propulsion may be by a cartridge that explodes and releases a gas through a cylinder, or by elastic cords. The aircraft is guided through the air either by a programmed onboard computer which controls the control surfaces of the aircraft and/or by remote control. The aircraft typically contains a camera for recording and transmitting images received from the ground below.

Aerodynamic Performance of Scale-Model Turbofan Outlet Guide Vanes Designed for Low Noise

Abstract: The design of effective new technologies to reduce aircraft propulsion noise is dependent on an understanding of the noise sources and noise generation mechanisms in the modern turbofan engine. In order to more fully understand the physics of noise in a turbofan engine, a comprehensive aeroacoustic wind tunnel test programs was conducted called the 'Source Diagnostic Test.' The text was cooperative effort between NASA and General Electric Aircraft Engines, as part of the NASA Advanced Subsonic Technology Noise Reduction Program. A 1/5-scale model simulator representing the bypass stage of a current technology high bypass ratio turbofan engine was used in the test. The test article consisted of the bypass fan and outlet guide vanes in a flight-type nacelle. The fan used was a medium pressure ratio design with 22 individual, wide chord blades. Three outlet guide vane design configurations were investigated, representing a 54-vane radial Baseline configuration, a 26-vane radial, wide chord Low Count configuration and a 26-vane, wide chord Low Noise configuration with 30 deg of aft sweep. The test was conducted in the NASA Glenn Research Center 9 by 15-Foot Low Speed Wind Tunnel at velocities simulating the takeoff and approach phases of the aircraft flight envelope. The Source Diagnostic Test had several acoustic and aerodynamic technical objectives: (1) establish the performance of a scale model fan selected to represent the current technology turbofan product; (2) assess the performance of the fan stage with each of the three distinct outlet guide vane designs; (3) determine the effect of the outlet guide vane configuration on the fan baseline performance; and (4) conduct detailed flowfield diagnostic surveys, both acoustic and aerodynamic, to characterize and understand the noise generation mechanisms in a turbofan engine. This paper addresses the fan and stage aerodynamic performance results from the Source Diagnostic Test.

Vorticity Control in Fish-like Propulsion and Maneuvering

Abstract: Vorticity control is employed by marine animals to enhance performance in maneuvering and propulsion. Studies on fish-like robots and experimental apparatus modelling rigid and flexible fins provide some of the basic mechanisms employed for controlling vorticity.

History of U.S. Navy Ramjet, Scramjet, and Mixed-Cycle Propulsion Development

Abstract: A history of high-speed airbreathing propulsion ramjet engines and their respective vehicle and weapon systems developed under the support of the U.S. Navy is presented. These include surface- and air-launched subsonic combustion ramjets, supersonic combustion ramjets (scramjets), and mixed-cycle ramjet/scramjet/rocket engines intended primarily for missile applications for flight speeds from Mach 2 to Mach 8. A summary of the development of the joint Department of Defense/NASA-sponsored National Aerospace Plane is also presented.

Monitoring and control of a pulse detonation engine using a diode-laser fuel concentration and temperature sensor

Abstract: Fuel measurements are needed to accurately tailor fued charges in pulse detonation engines (PDEs) to improve engine performance and to validate PDE models and computations. Here, we report simultaneous concentration and temperature measurements of C2H4 fuel in a PDE using a newly developed diode-laser absorption sensor. These measurements enable characterization of the fuel loading and ignition timing of the engine. Based on these characterizations, a real-time control system that optimizes fuel consumption and maximizes specific impulse in the engine has been realized. Similar measurements of C2H4 concentration and temperature were used to characterize pulse-to-pulse interference resulting from loading fresh fuel/oxygen reactants into hot combustion products. The sensor was used in a simple control scheme to minimize such interference, illustrating its potential role in control systems to maximize the engine's operation rate. During these studies, the sensor demonstrated two valuable improvements over traditional absorption spectroscopic techniques: (1) increased robustness and accuracy and (2) simultaneous measurements of concentration and temperature. These improvements are enbled by broad wavelength scanning of the Q-branch spectra of C2H4 near 1.62 μm. The success achieved in these small-scale tests provides strong support for expanded use of diode-laser sensors in propulsion applications.

Integrated and/or modular high-speed aircraft

Abstract: An integrated and modular high-speed aircraft (200) and method of design and manufacture. The aircraft (200) can have a supersonic or near-sonic cruise Mach number. In one embodiment, the aircraft (200) can include an aft body integrated with a delta wing (204) and a rearwardly-tapering fuselage (202) to define a smooth forward-to-rear area distribution. A propulsion system (206), including an engine (216), inlet (220), and exhaust nozzle (222) can be integrated into the aft body to be at least partially hidden behind the wing (204). In one embodiment, the entrance of the inlet can be positioned beneath the wing (204), and the exit of the nozzle (222) can be positioned at or above the wing (204). An S-shaped inlet duct (221) can deliver air to the aft-mounted integrated engine.

Drive configuration for a skid steered vehicle

Abstract: An electric drive configuration for a skid steered vehicle comprises; a pair of propulsion motors (74a, 74b), each with a motor shaft protruding from both ends of the motor and mounted on the same axis across the vehicle, each being coupled at the outer end to drive one of a pair of tracks or set of wheels of the skid steered vehicle; a control differential steer gear unit (72) positioned between the two propulsion motors and in driveable communication with the inner ends of the two motor shafts; and a steer motor (71) in driveable communication with the controlled differential (72), the steer motor (71) being controllable from zero speed giving straight line running in which both motor shafts are coupled to run at the same speed, to a range of speeds in both directions of rotation giving steering capability in both directions.

Micropropulsion for Space — A Survey of MEMS-based Micro Thrusters and their Solid Propellant Technology

Abstract: In the last two decades, advances in microsystems technology have made micro mechanics mature enough to envisage miniaturization in the space industry. The motivation behind this development is the reductions in mass, satellite costs and launch costs in parallel with an increase in the reliability and flexibility of satellites. A cluster of many small satellites, commanded from a mothership, or totally independent, will, without any doubt, reduce the risk of mission failure and increase mission flexibility. This revolution in the space industry will rely on propulsion system development to ensure the maneuvering and fine positioning of micro and nano satellites (defined as satellites with mass between 20—100 kg and under 20 kg, respectively). This paper is provides a state-of-the-art review of micro thruster technologies for space applications. the intention is to overview the different technical solutions under investigation in the micropropulsion field, to assess their merits and disadvantages and to try to identify the promising ones in relation to future missions needs. First, the principles of propulsion and basic concepts and equations useful in describing and comparing propulsion systems are described. Then, a review micropropulsion needs for space is made and the options and technologies available for propulsion are presented. An outline is given of the technological efforts made in miniaturizing propulsion systems through examples from current research programs and the different micropropulsion technologies are compared. After illustrating the assets of microsystem technology in the micropropulsion field by the detailed presentation of one particular micropropulsion option investigated at LAAS-CNRS, namely solid propellant micro thruster arrays, a short discussion is given of the capability of microsystem technology to serve micropropulsion needs.

A new technique for multi-dimensional performance optimization of switched reluctance motors for vehicle propulsion

Abstract: This paper presents a new and simple search technique to determine the optimum control parameters, such as turn-on and turn-off angles, current set level, etc., of a switched reluctance drive. Thanks to this new technique, several drive performance quantities such as efficiencies, torque ripple, energy consumption, torque per ampere, etc., can be optimized simultaneously over the entire torque- or power-speed operation range of the drive. In prior work, these performance quantities were sequentially optimized, one at a time, this despite reported evidence that improving one performance quantity, such as efficiency, can have a negative impact on others, such as torque ripple. The technique was successfully used offline to determine the optimum firing angles for achieving highest drive efficiency with lower torque ripple in a 102-kW switched reluctance motor drive intended for electric vehicle propulsion. The performance prediction and test results are found in good correlation.

Technology Roadmap for Dual-Mode Scramjet Propulsion to Support Space-Access Vision Vehicle Development

Abstract: Third-generation reusable launch vehicle (RLV) systems are envisioned that utilize airbreathing and combined-cycle propulsion to take advantage of potential performance benefits over conventional rocket propulsion and address goals of reducing the cost and enhancing the safety of systems to reach earth orbit. The dual-mode scramjet (DMSJ) forms the core of combined-cycle or combination-cycle propulsion systems for single-stage-to-orbit (SSTO) vehicles and provides most of the orbital ascent energy. These concepts are also relevant to two-stage-to-orbit (TSTO) systems with an airbreathing first or second stage. Foundation technology investments in scramjet propulsion are driven by the goal to develop efficient Mach 3-15 concepts with sufficient performance and operability to meet operational system goals. A brief historical review of NASA scramjet development is presented along with a summary of current technology efforts and a proposed roadmap. The technology addresses hydrogen-fueled combustor development, hypervelocity scramjets, multi-speed flowpath performance and operability, propulsion-airframe integration, and analysis and diagnostic tools.

MAGLEV projects technology aspects and choices

Abstract: This papers presents technology aspects and choices relative to worldwide MAGLEV projects such as the German Transrapid, the Japanese MLX, the USA Inductrack and the Swissmetro. Propulsion, magnetic levitation and guidance, transfer of energy to the vehicle are investigated.

Cycle with auxiliary propulsion

Abstract: The invention relates to a cycle, comprising: a frame, one or more wheels arranged rotatably on the frame via wheel axles, drive means for driving the wheels wholly or partly with human force via transmission means, wherein a power source and/or an auxiliary propulsion forming part of the drive means are arranged in or on the cycle in a manner which is as invisible as possible from the outside.

Ducted vehicles particularly useful as vtol aircraft

Abstract: A VTOL aircraft (10) (or other vehicle such as a sea vehicle) includes a pair of elongated ducts on opposite sides of the vehicle body, and a plurality of powered propellers (or other propulsion units such as jet engines) mounted within and enclosed by each of the elongated ducts (134a, 13b), such as to produce an upward lift force to the vehicle Each of the elongated ducts has a short transverse dimension slightly larger than the diameter of the blades of each propeller (14, 15) enclosed thereby, and a large transverse dimension slightly larger than the sum of the diameters of the blades of all the propellers enclosed thereby

The Advanced Induction Motor

Abstract: The ALSTOM Advanced Induction Motor has evolved over a period of around 15 years, during which time function and performance have steadily improved. In the electric warship, compactness of the propulsion motor is important, but so also must be reliability, structureborne noise signature, and shock withstand ability. This has been achieved in the Advanced Induction Motor through optimization of the electromagnetic design and material properties to suit the operating conditions of a propulsion motor. One of the advantages of an induction motor is its mechanical simplicity. This leads to not only to inherent reliability, but also to simpler design for shock requirements. Through careful motor and system design, it has been possible reduce structureborne noise signatures to levels that permit hard mounting of the motor to the hull of a surface combatant. The paper reviews the evolution of the Advanced Induction Motor from industrial induction motors, and the considerations necessary to achieve low noise signature and shock requirements.

Naval combat survivability testbeds for investigation of issues in shipboard power electronics based power and propulsion systems

Abstract: There are numerous issues involved in the design of power electronics based power distribution and propulsion systems. These issues include power density, dynamic stability, efficiency, acoustic and waterborne noise, and electromagnetic compatibility, to name a few. In order to address these issues, as well as to test CAD tools for designing these systems, two reduced scale hardware test beds have been developed. The first of these, the Naval Combat Survivability Generation and Propulsion Testbed, focuses on primary power generation and propulsion. The second of these, the Naval Combat Survivability DC Distribution test bed, focuses on DC power distribution using a zonal architecture.

Boat propulsion system

Abstract: The invention relates to a boat propulsion system comprising at least one propeller (8), at least one electric motor (7) by means of which the at least one propeller can be driven, and one converter-fed power supply unit. The at least one electric motor (7) can be supplied with electric power by means of said power supply unit which comprises at least one prime mover and at least one generator powered by said prime mover. The at least one electric motor and the at least one generator of the power supply unit are embodied as three-phase synchronous machines. In order to reduce the volume and weight of such a boat propulsion system while increasing its effectiveness, the at least one electric motor (7) that is configured as a three-phase synchronous machine and the at least one generator that is configured as a three-phase synchronous machine of the power supply unit have rotating excitation coil (10) made of high-temperature super conductor wire and each rotating excitation coil (10) made of high-temperature super conductor wire is arranged in a vacuum-tight, insulated cryostat (14) by means of which the rotating excitation coil (10) made of high-temperature super conductor wire can be chilled to a temperature of 15 to 77 K.

Engine System Performance of Pulse Detonation Concepts Using the NPSS Program

Abstract: The Numerical Propulsion Systems S imulation (NPSS) tool has been used to analyze several Pulse Detonation Engine (PDE) concepts that have been of interest lately The PDE cycle approximates a constant volume combustion process which results in both a temperature and pressure rise across t he device In this study, the PDE was modeled using standard shock tube relationships and flow into and out of the device was assumed to be steady state The capabilities of NPSS in modeling this concept will be discussed An analysis was completed comp aring a PDE to a conventional ramjet For the purposes of the study, the PDE was modeled as a ramjet with a detonation chamber instead of the conventional combustor (basic PDE) Comparisons were made on thrust, specific fuel consumption (SFC), and engine pressure ratio over a range of peak temperatures The unsteady flow characteristic of the PDE has the potential to degrade inlet and nozzle performance relative to steady flow A short parametric study was completed to gauge the overall performance impa ct of changes to inlet and nozzle performance The incorporation of a detonation tube into the core of a high bypass turbofan engine (~100,000 lb thrust class) was also investigated Thrust and SFC comparisons are made along with comments on changes req uired to the system in order to incorporate such a device into a high bypass turbofan engine Finally, a brief discussion is included on the usefulness of this level of analysis of PDE concepts Areas of concern will be noted with possible workarounds id entified NPSS Analysis Tool

Vehicle and Mission Design Options for the Human Exploration of Mars/Phobos Using "Bimodal" NTR and LANTR Propulsion

Abstract: The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars because of its high specific impulse (1sp is approximately 850-1000 s) capability and its attractive engine thrust-to-weight ratio (approximately 3-10). To stay within the available mass and payload volume limits of a "Magnum" heavy lift vehicle, a high performance propulsion system is required for trans-Mars injection (TMI). An expendable TMI stage, powered by three 15 thousand pounds force (klbf) NTR engines is currently under consideration by NASA for its Design Reference Mission (DRM). However, because of the miniscule burnup of enriched uranium-235 during the Earth departure phase (approximately 10 grams out of 33 kilograms in each NTR core), disposal of the TMI stage and its engines after a single use is a costly and inefficient use of this high performance stage. By reconfiguring the engines for both propulsive thrust and modest power generation (referred to as "bimodal" operation), a robust, multiple burn, "power-rich" stage with propulsive Mars capture and reuse capability is possible. A family of modular bimodal NTR (BNTR) vehicles are described which utilize a common "core" stage powered by three 15 klbf BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration / reliquification system for long term, zero-boiloff liquid hydrogen (LH2) storage, and high data rate communications. An innovative, spine-like "saddle truss" design connects the core stage and payload element and is open underneath to allow supplemental "in-line" propellant tanks and contingency crew consumables to be easily jettisoned to improve vehicle performance. A "modified" DRM using BNTR transfer vehicles requires fewer transportation system elements, reduces IMLEO and mission risk, and simplifies space operations. By taking the next logical step--use of the BNTR for propulsive capture of all payload elements into Mars orbit--the power available in Mars orbit grows to 150 kWe compared to 30 kWe for the DRM. Propulsive capture also eliminates the complex, higher risk aerobraking and capture maneuver which is replaced by a simpler reentry using a standardized, lower mass "aerodescent" shell. The attractiveness of the "all BNTR" option is further increased by the substitution of the lightweight, inflatable "TransHab" module in place of the heavier, hard-shell hab module. Use of TransHab introduces the potential for propulsive recovery and reuse of the BNTR / Earth return vehicle (ERV). It also allows the crew to travel to and from Mars on the same BNTR transfer vehicle thereby cutting the duration of the ERV mission in half--from approximately 4.7 to 2.5 years. Finally, for difficult Mars options, such as Phobos rendezvous and sample return missions, volume (not mass) constraints limit the performance of the "all LH2" BNTR stage. The use of "LOX-augmented" NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen mixture ratio (MR) of 0.5, helps to increase "bulk" propellant density and total thrust during the TMI burn. On all subsequent burns, the bimodal LANTR engines operate on LH2 only (MR=0) to maximize vehicle performance while staying within the mass limits of two Magnum launches.

Magnetic discretion of naval propulsion machines

Abstract: Magnetic silencing is required for specific naval applications, especially for some oceanographic or military ships It is therefore necessary to study the field radiated by electrical propulsion motors This can be achieved using a numerical modeling based on magnetic moments In the present paper, this model is presented and then compared to some experimental signatures for validation

Running control device

Abstract: A running control device for a watercraft controls propulsion force and tilt angle of a propulsion device relative to the hull of the watercraft. The running control device also sets an optimum trim angle automatically. The running control device includes a propulsion force control section that controls the propulsion force of the propulsion device. The running control device also includes a tilt angle control section that controls the tilt angle of the propulsion device. A target propulsion force calculation module responds to first input information (e.g., watercraft velocity) to calculate a target propulsion force. An amount-of-operation calculation module responds to second input information to calculate an amount of operation of the propulsion device to produce the target propulsion force. The tilt angle control section includes a tilt angle calculation module that determines the tilt angle based on the propulsion force.